<template>
    <div class="spec-preview">
        <img :src="imageUrl"/>
        <div class="event" @mousemove="handler"></div>
        <div class="big">
            <img :src="imageUrl" ref="big"/>
        </div>
        <!--遮罩层-->
        <div class="mask" ref="mask"></div>
    </div>
</template>

<script>
export default {
    name: "Zoom",
    props: ['skuImageList'],
    data() {
        return {
            currentIndex: 0
        }
    },
    computed: {
        imageUrl() {
            return this.skuImageList[this.currentIndex]?.imgUrl
        }
    },
    mounted() {
        this.$bus.$on('getIndex', (index) => {
            this.currentIndex = index
        })
    },
    beforeDestroy() {
        this.$bus.$off('getIndex')
    },
    methods: {
        handler(event) {
            let mask = this.$refs.mask
            let big = this.$refs.big
            let left = event.offsetX - mask.offsetWidth / 2
            let top = event.offsetY - mask.offsetHeight / 2
            if (left < 0) left = 0
            if (top < 0) top = 0
            if (left > mask.offsetWidth) left = mask.offsetWidth
            if (top > mask.offsetHeight) top = mask.offsetHeight
            //修改元素的left和right
            mask.style.left = left + 'px'
            mask.style.top = top + 'px'
            big.style.left = -2 * left + 'px'
            big.style.top = -2 * top + 'px'
        }
    }
}
</script>

<style lang="less">
.spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
        width: 100%;
        height: 100%;
    }

    .event {
        width: 100%;
        height: 100%;
        position: absolute;
        top: 0;
        left: 0;
        z-index: 998;
    }

    .mask {
        width: 50%;
        height: 50%;
        background-color: rgba(0, 255, 0, 0.3);
        position: absolute;
        left: 0;
        top: 0;
        display: none;
    }

    .big {
        width: 100%;
        height: 100%;
        position: absolute;
        top: -1px;
        left: 100%;
        border: 1px solid #aaa;
        overflow: hidden;
        z-index: 998;
        display: none;
        background: white;

        img {
            width: 200%;
            max-width: 200%;
            height: 200%;
            position: absolute;
            left: 0;
            top: 0;
        }
    }

    .event:hover ~ .mask,
    .event:hover ~ .big {
        display: block;
    }
}
</style>